1. Field of the Invention
The present invention relates to a process for producing styrene polymers, more particulary to a process for producing styrene polymers having a high degree of syndiotactic configuration with a wide molecular weight distribution, by a polymerization reaction using specified catalysts in a comparatively simple step.
2. Description of the Related Arts
Styrene polymers have heretofore been widely used as materials of various moldings. Especially, styrene polymers having a syndiotactic configuration are excellent in physical properties such as heat resistance and water resistance, so utilizations of said polymers have attracted attention.
As the process for producing such styrene polymers having a syndiotactic configuration, a process for polymerizing with the use of catalysts containing titanium compound and alkylaluminoxane as main components (Patent Application Laid-Open No. 187708/1987) has been found. However, though the styrene polymer having a syndiotactic configuration produced according to said process have a high syndiotacticity, its molecular weight distribution was narrow such as weight average molecular weight (Mw)/number average molecular weight (Mn)=1.5 to 3.0. As for styrene polymers having a narrow molecular weight distribution thus obtained, there has been no problem in injection molding, but there have been problems such as draw down or a large neck-in, in hollow molding, and sheet and film molding.
The present inventors have studied earnestly to produce styrene polymers which are suitable for hollow molding, sheet and film molding, and have a wide molecular weight distribution and a high syndiotacticity. As the result, it has been found that the object can be attained by polymerization reaction with the use of catalysts containing not less than two kinds of titanium compounds and alkylaluminoxane. The present invention has been accomplished according to these knowledges.